The studies described are designed to define a defect in the peripheral blood monocyte function associated with chronic mucocutaneous candidiasis. Subsequent experiments will assess whether a similar dysfunction occurs in monocytes from patients with other forms of Candida yeast infection. A second objective of this study deals with the possible effects of yeast mannan on host defense systems, including cell-mediated immune responses and neutrophil functions. Mannan will be isolated from patients sera, fractionated, and the biological effects of the various components tested. Mannan derived from baker's yeast, Saccharomyces cerevisiae, will also be studied in this fashion, as preliminary studies in our laboratory indicate that mannan polysaccharide from both sources has significant inhibitory effects on the host defense system.